WOOD AND ROME LINCOLNSHIRE AND 8.E. YORKSHIRE. 147 



II. The Structure of South-east Yorkshire and North-bast 

 Lincolnshire. 



As all the beds of this region appear to us to be represented in the 

 Holderness coast-section (fig. 1, p. 148), their description will be 

 much shortened if we give a condensed view of the section afforded 

 by the line of coast from the mouth of the Humber to Speeton, the 

 point where the Northern Wold-scarp and foot is intersected by the 

 present coast. 



The bed marked a of this section, or basement clay of Holderness, 

 forms the oldest of all the deposits above the chalk in these parts. 

 It consists of a lead-coloured clay abounding in chalk debris, 

 accompanied by stones and boulders from all sorts of rocks ; and it 

 presents a close resemblance to that wide-spread Boulder-clay of the 

 eastern and east-central counties which is referred to by the first- 

 named of us, in the last volume of the Journal*, as the " Upper 

 Glacial Clay," with which deposit we identify it. This clay (a) rises 

 up in only a few parts of the coast, and is overlapped in every 

 direction by another thick bed of Boulder-clay, marked c in the 

 section, to which in most of its exposures it presents a very denuded 

 surface, rising up beneath it in bosses, and in some places divided 

 from it by the beds marked 6. The relation borne to each other by 

 these clays will appear by a comparison of fig. 1 with the eastern 

 extremities of figs. 5 and 11, both of which cut the deposit at 

 right angles to the former. This basement clay, like the Upper 

 Glacial clay of the eastern and east-central counties, appears to be 

 destitute of any but derivative organic remains. 



The beds h, which occupy some of the depressions formed by 

 denudation in the surface of the basement clay, and sometimes spread 

 irregularly over the bosses, consist of sand with occasional gravels. 

 In some parts their place is taken by bands of clay (partially separated 

 by sands) exhibiting a character intermediate between the clays a 

 and c. Not unfrequently, however, it is difficult to say where the 

 basement clay (a) ends, and the purple clay (c) begins ; but in 

 other parts the division is very distinct, and the surface of the former 

 is deeply eroded. Nothing whatever exists, to our apprehension, that 

 would suggest any identity between the beds h and the thick and 

 continuous Middle Glacial formation of the east of England ; but the 

 reverse of this seems from the general structure to follow, the beds 

 h being over the clay which we identify with the Upper Glacial clay 

 of the east of England, while the Middle Glacial formation is under 

 the latter. We have not been able to detect any organic remains in 

 the beds h, or to learn of any having been procured from them. 



The clay formation c, which, from its prevailing colour of purplish 

 brown, we term the " purple clay," is that which has the most 

 extensive spread of any bed superior to the chalk in Yorkshire, not 

 only overlapping the basement clay in all directions, but extending far 

 beyond the north scarp of the Wolds in an irregular belt along the coast 

 northwards. It seems to us to be the same clay as that which appears 

 at intervals along the coast as far as the mouth of the Tees, to near 

 * Quart. Journ. Geol. Soc. vol. xxiii. p. 394 et seq. 



VOL. IXIV. PART I. M 



